MAX2102 Evaluation Kit

2

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__________Test Equipment Required

• RF-signal generator to generate the RF-carrier sig-

nals, with 950MHz to 2150MHz frequency range and

-69dBm to -19dBm power range.

• RF-signal generator to generate the LO signal, with

950MHz to 2150MHz frequency range at -10dBm.

• (Optional) RF balun, such as Anzac H-9, if testing

the MAX2102 with a differential LO drive.

• Dual-channel digitizing oscilloscope with 50Ω termi-

nated inputs and 100MHz minimum bandwidth for

time-domain baseband measurements. In addition,

a high-frequency, high-impedance probe is required

if monitoring the prescaler.

• Network/spectrum analyzer capable of measuring

30kHz to 100MHz signals for frequency-domain

baseband measurements.

• +5V power supply that can deliver a minimum of

300mA.

• Adjustable voltage source that can supply a 1V to

4V range and source and sink 500µA for automatic

gain control (AGC).

Connections and Setup

Ensure that the RF signal generators are disabled, and

that the power supplies are off until all connections are

made.

1)

Connect the +5V power supply to J7 (“VCC”).

Connect ground to J8 (“GND”).

2)

Ensure that there are no shunts installed at JU2 or

JU3.

3)

Connect the variable voltage source to the pad

labeled “AGC.” Ensure that the voltage source’s

ground is connected to J8.

4)

Connect an SMA cable from the LO signal-

generator source to SMA connector J4 (LO) on the

board. A 6dB attenuator connected in-line between

J4 and the cable is recommended to minimize

reflections that could affect power-level control on

some signal generators. See the section

Using a

Differential Oscillator Source for information on driv-

ing the LO port differentially.

5)

Connect an SMA cable from the RF-carrier signal-

generator source to SMA connector J2 (RFIN).

A 6dB pad between J2 and the cable is recom-

mended.

6)

Connect two cables of equal length from the dual-

channel oscilloscope inputs to BNC connectors J1

and J3 (“IOUT,” “QOUT”). Ensure that the oscillo-

scope inputs are 50

Ω.

7)

Set up the instruments:

—Set the RF-carrier signal source to deliver

950MHz at -30dBm at RFIN. Be sure to account

for attenuator and cable losses.

—Set the LO signal source to deliver 950.125MHz

at -10dBm at LO. Be sure to account for attenua-

tor and cable losses.

—Set up the oscilloscope to view a 125kHz sine

wave at 0.5Vp-p full scale, triggered from either

the “IOUT” or “QOUT” signal.

8)

Turn on the power supplies and enable the signal

generators.

9)

Adjust the AGC control voltage until the IOUT and

QOUT signals are approximately 0.25Vp-p.

Analysis

AGC

Vary the RF-carrier signal-generator power over the

-19dBm to -69dBm range. Use the AGC voltage control

(in a 1V to 4V range) to keep the IOUT and QOUT sig-

nals in the 0.25Vp-p range.

Note (from the EV kit schematic) that the board in-

cludes 47

Ω resistors (R1, R7) in series with the base-

band IOUT and QOUT outputs, which results in a 6dB

attenuation with the cable terminated to 50

Ω at the

oscilloscope. The actual voltage swing per carrier is

0.5Vp-p at the MAX2102’s IOUT and QOUT pins.

Vary the LO and RFIN frequency over the 950MHz to

2150MHz range, maintaining 125kHz between RFIN

and LO. Observe that over 50dB, AGC range is main-

tained across the frequency band.

Quadrature Accuracy

The difference in phase between the IOUT and QOUT

baseband signals should be 90°, with Q lagging I if the

LO frequency is greater than the RFIN frequency.

Using both the oscilloscope’s DELAY measurement

function and averaging, determine the quadrature

phase mismatch (deviation from 90°).

The baseband frequency is 125kHz. At higher base-

band frequencies, the delay between IOUT and QOUT

becomes more difficult to measure accurately.

Additionally, phase error due to small differences in

group delay in IOUT and QOUT measurement channels

becomes more pronounced. Therefore, low baseband

frequencies are suggested when making this measure-

ment.